Keep only base/extractor.[cc|h].

base/program_instance.cc

-// Copyright 2005-2010 Google Inc.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-// ========================================================================
-
-// The class uses a singleton mutex, with a local name in the user session, to
-// prevent multiple instances of a program.
-
-#include "omaha/base/program_instance.h"
-#include "omaha/base/debug.h"
-
-namespace omaha {
-
-bool ProgramInstance::EnsureSingleInstance() {
-  return CheckSingleInstance();
-}
-
-bool ProgramInstance::CheckSingleInstance() {
-  ASSERT1(!mutex_name_.IsEmpty());
-
-  reset(mutex_, ::CreateMutex(NULL, false, mutex_name_));
-  if (!mutex_) {
-    // We were not able to create the mutex instance for some reason.
-    return false;
-  }
-  DWORD error = ::GetLastError();
-  if (error == ERROR_ALREADY_EXISTS) {
-    // The program instance is already running since the mutex already exists.
-    return false;
-  }
-  return true;
-}
-
-}  // namespace omaha